Is this normal? Buddies car is breakin up at higher Rs and the pump was just replaced a week ago with a racetronix unit. wondering if it is faulty, didnt think FP was supposed to do this?

 

41-47psi at idle, with no vacuum line connected. Connect the vacuum line and the pressure should drop 5 to 8psi below the no vacuum reading. As throttle opens (MAP increases/vacuum decreases), pressure should approach the "no vacuum" value, not drop.

 

So it sounds like a bad pump then eh....hope racetronix offers a warranty on this. Thanks Fred.

 

i got the same issue. so pressure shouldnt drop at all?

 

The pressure in the rails (what you see when you attach a fuel pressure gauge to the Scrader valve) should be equal to 43.5psi (or your "no vacuum" setting), MINUS the intake manifold vacuum. At idle, you have 20"Hg vacuum, so the pressure in the rails drops by 8psi or so. As you open the throttle, vacuum disappears, and the rail pressure should return "close to" the pressure you measured with no vacuum line connected. It will never return all the way to the "no vacuum" reading, because there is always some small amount of vacuum in the intake manifold, depending on the pressure losses in your air intake track.

The injector only flows the rated amount when the pressure in the rails, minus the pressure in the intake is 43.5psi. That's why the vacuum line is there..... to keep the difference between the rail pressure and the discharge point of the injector into the intkae runner at a constant 43.5psi.

 

Fuel pressure should increase as the RPM goes up/engine vacuum decreases. Are you sure it's the pump and not the regulator?

 

Assuming you have a N/A motor...
If you rev the motor with no load the vacuum will go up and the fuel pressure down. There will be a slight blip increase just as you tap the throttle but FP goes down from there..

 

so i set my fuel pressure to 43-45psi, when revvin its normal for the pressure to drop 4-5psi? some are saying it should rise 4-5psi... im confused now. i havent had a chance to watch the guage under a load to see if its different.

 

Alright, stuck a fuel press gauge out the window and it drops to about 10psi at like 4000 under load, so the pump is 99% shot, not to mention the 150db whine that comes on when you turn the key forward coming from the fuel pump.

Anyway, wanted to make sure the regulator cant regulate that low and be 100% sure its the pump before we pursue this further.

Also, Racetronix, if you get back in here, is there any way we can warranty this pump or does that not happen? If you see this could you give him a call at 419-349-5129, would be appreciated, thanks.

 

Although Walbro has killed their warranty program Racetronix is still offering warranty. The stipulation is that before any pump is sent out as a replacement we must receive the failed pump back or take a deposit equivalent to the cost of the fuel pump assembly ($149.99). Walbro killed their warranty program because 98% of all pumps sent back were found to be not defective and of the small % that were most had failed due to being run dry (scored armature brushes & gears) or contamination (rust etc.) Once we receive the failed pump back, test it and if required inspect the internals and do not find any signs of abuse we will ship out a new replacement pump assembly OR credit the deposit depending on the customer's method of choice.

If you pull your pump from the tank and you find that the filter sock is tan and the flex tube discolored there is a good chance the pump failed due to rust contamination. This is the NUMBER ONE reason why we DO NOT recommend the trap door method as it does not allow the tank to be flushed and thoroughly cleaned prior to installing the new pump. Looking down into the tank will not provide evidence of powdered rust in the tank. Due to the age of the F-LT1 gas tanks rust is the # 1 cause of pump failure.

Please contact support@racetronix.com for warranty info and the required details to RMA your pump assembly.

Jack
Racetronix

 

My buddy had a problem like that once after he installed a pump. It turn out the small hose from the pump to the hard line had slipped off. It was also really loud. Pulled it out, put a clamp on it and hasn't had a problem since.